In the production of beer or malt liquors, a wort producing step comprises milling a malt and a rice, a wheat, a corn, a starch and the like as secondary raw materials, reacting the mixture with an enzyme in the malt or a foreign enzyme, then removing grain husks or coagulated matters, and boiling the resulting wort in a boiling kettle (boiling apparatus) together with a hop.
In the procedure of boiling the wort, (1) a bitter taste or a flavor contained in the hop added is applied, (2) a coagulable protein in the malt is coagulated to clarify the liquid, (3) deactivation of the enzyme remaining in the wort and sterilization of the wort are conducted, and (4) removal of excess water through evaporation and removal of volatile matters which are undesirous to the flavor through volatilization and exhalation are conducted.
With respect to the degree of volatilization and exhalation of volatile matters in (4), among the above-mentioned, an evaporation rate of water has been so far employed as one standard. That is, volatile matters derived from raw materials such as a malt, a hop and the like are volatilized and exhaled in combination with evaporation of water. Further, a degree of volatilization and exhalation of these volatile matters is interpreted to be in an amount having some relationship with an evaporation rate of water.
Meanwhile, as a method of directly finding amounts of volatile matters to be volatilized and exhaled, there is a method in which an amount decreased (residual amount) of dimethyl sulfide (hereinafter abbreviated as "DMS"), one of volatile matters, in a wort after boiling is measured, and a degree of evaporation of the overall volatile matters is estimated from this measured value.
According to this method, the wort boiling condition can be evaluated from the residual amount of DMS.
However, this method could not evaluate the volatilization and exhalation efficiency of the wort with a general standard.
That is, when the volatilization and exhalation efficiency of volatile matters in the wort boiling operation is evaluated, it is required that upon unifying the boiling conditions in the boiling step, the evaluation is conducted on the basis of the amount of DMS decreased in this boiling step. When the scale and the conditions are different in each boiling apparatus, the comparative evaluation of the exhalation efficiency cannot be conducted by the above-mentioned conventional method.
The present invention aims at, for solving the above-mentioned conventional problems, analyzing the reaction and the change from formation of DMS in a wort to exhalation of the same into a gaseous phase and determining an evaluation standard which is not influenced by boiling conditions.
In other words, it is an object of the present invention to provide a method of evaluating a separation and exhalation performance of volatile matters in a boiling apparatus used in the production of beer or malt liquors, in which a degree of whether or not a boiling control method of a boiling apparatus, a structure of a boiling apparatus or the like is appropriate for separation and exhalation of volatile matters is evaluated depending on an exhalation efficiency (exhalation rate) of volatile matters in boiling a wort during the production of beer or malt liquors.